Method for repairing cracked hollow metallic bodies



Sept. 27, 1949. MERCER 2,482,925

METHOD FOR REPAIRING CRACKED HOLLQW METALLIC BODIE$ Filed June 16, 19452 Sheets-Sheet 1 n w m m M M n M ww. 4 I\3 H Mm W.

Sept. 27, 1949.

D. A. MERCER METHOD FOR REPAIRING CRACKED HOLLOW METALLIC BODIES 2Sheets-Sheet 2 Filed June 16, 1945 .m y R mm 5 N M N E V 2 WM 0 w r A YE 4 m .0

Patented Sept. 27, 1949 METHOD FOR REPAIRING CRACKED HOLLOW METALLICBODIES Dudley Anson Mercer, Bloomington, Ind., assignor to MoguloidCompany 01' America, Chicago, III., a copartnership Application June 16,1945, Serial No. 599,908

5. Claims.

This invention relates to a method for repairins cracked hollow metallicbodies.

It is the primary object of the invention to provide a method of thecharacter described for effecting repairs quickly, economically andsimply, and in such manner that the same will not reopen when subjectedto severe stresses, sudden or large temperature changes, or vibration.

Other objects of the invention will in part be obvious and in parthereinafter pointed out.

The invention accordingly consists in the features 01' construction;combinations of elements, and arrangement of parts which will beexemplified in the construction hereinafter de-- scribed, and of whichthe scope of application will be indicated in the appended claims.

In the accompanying drawing, in which is shown one of the variouspossible embodiments of this invention,

Fig. 1 is a sectional view through a crack in an automobile engine blockbetween a valve port and a cylinder;

Figs. 2, 3 and 4 are similar views of said block at successive stages inthe repair of the crack;

Fig. 4a is a sectional view taken substantially along the line lit-4a ofFig. 4;

Fig. is a side view of the block with a plate mounted thereon to blockof! openings in the water jacket preparatory to introducing into theblock a fluent pore-sealing material;

Fi'g. 6 is a top plan view of said block and plate; and

Fig. '1 is an enlarged sectional view taken substantially along the line1-1 of Fig. 6.

In general, the invention is carried out by practicing the followingsteps: (1) locating the crack, (2) isolating the crack from the soundportion of cracked body, (3) inserting pins to prevent relative movementof the walls of the crack in the direction of the crack, (4) channelingout the exposed side of the crack, (5) depositing sufllcient metal inthe resulting groove by electric bonding to restore the originalsurface, and (6) sealing the pores in the deposited metal and the finecrevices around the pins.

Locating the crack The position and course of the crack conveniently maybe ascertained by cooling the cracked body, thus causing the same tocontract and increasing the space between the walls of the crack. Undersome circumstances, the crack may be so situated that the application ofcold tends to close the crack and in these cases the 2 crack can befound by heating the body. The body may be heated or chilled in anysuitable manner, and the way in which heating or cooling is performedwill, to a considerable extent, de-

pend upon the type of the body which is being v repaired. Thus, if thebody is an engine block such as is illustrated herein, or a cylinderhead, the same is most easily heated or cooled by introducing a heatingor cooling medium in the water jacket. For example, to chill an engineblock, cool or even ice water can be circulated through the waterjacket. To heat the block, hot water or steam can be introduced intosaid jacket.

In Fig. 1 there is shown a crack II! which has been located in the blockl2 of an automobile engine. The course of said crack is from a valveseat and port M to a cylinder I6. A part of the crack runs across thetop surface of the block. Said block has the customary circulatingpassageways I8, 20 which form a water jacket surrounding the cylindersand valves. As is usual, the crack extends from the outside surface ofthe block to the hollow interior thereof.

Isolating the crack The next step in the practice of the invention is tofix the position of the crack by separating the intracrystalline orcrystalline lines of cleavage, that present themselves at the time offracture, from the normal structure of the sound metal. crack in thebody is prevented and the damaged area is isolated from th remainingsound portion of the body. Such isolation is accomplished, according tothe invention, byproviding fixing pins 22, 24, one at each end of thecrack Ill. Preferably these pins are applied by first boring terminalholes 23 in the crack at the ends thereof. Said holes are so positionedthat the ends of the crack terminate in directions approximatelynormalto the walls of the holes, whereby the ends of the crack appear tobe diametrically disposed with respect to the holes and the walls ofeach hole are cracked at only one place. If desired, the terminal holesmay be smooth and smooth fixing pins driven therein. In such case thepins should be large enough so that they have to be force-fitted. Thisis accomplished by having the pins made slightly larger in diameter thanthe holes and, since blocks are usually cast and therefore relativelyfragile, making the pins of metal soft enough to be forced into the holewithout further cracking th block. A pin of low carbon annealed steel issatisfactory for this In this manner, the progression of the purpose.The pins also may be slightly tapered.

Alternatively, the holes 23 may be tapped and the fixing pins 22, 24have threads provided thereon so that said pins can be screwed tightlyinto the holes and firmly held in place. In this latter case, the pinsor the holes may be slightly tapered to make sure that when the pins aretightened, they are rigidly secured in place.

Preventing relative movement of the ioallsiol the crack in the directionof the crack Either before or after the fixing pins 22, 24 are inserted,limit pins 26, 28 are applied. The function of these latter pins is toprevent relative movement in the direction of the crack between theportions of the metal body at the two sides of the crack. Said limitpins take up any stresses which may be induced into the body in theregion of the repair. Accordingly, limit pins are placed wherever stressin tension, compression or shear, which might cause relative movement ofthe walls of the crack, could arise in the body after repair, regardlessof the nature of the force giving rise to the stress. Such stressesusually are caused by thermal expansion or contraction, vibration ordirect application of a strain. Such stresses also are created byapplying a strain to a bend, and particularly to an abrupt bend. Placeswhere stresses of this nature occur are well known to the automobilemechanic. For example, such stresses arise at and near the point ofapplication of a load, resulting, for example, from an explosion in thecylinder or tightening the cylinder head on the engine block. Suchstresses also might arise where the crack runs along an unsupported spanfor about one inch or more or extends around a corner connecting twowalls, e. g., the top surface of the block and the cylinder wall. Apoint of high stress will be encountered where there is a sudden changein the temperature of the body. Good results are obtained where the pinsare spacd an inch apart over the length of the crack.

The two main spots where a disloc'ating stress is most likely to occurin the crack Eli are the points 30, 32 at the valve seat and edge of thecylinder, respectively.

Therefore, according to my invention holes 21 are bored at said pointsand limit pins 26, 28 inserted in said holes. As in the case of thefixing ins 22, 24, the limit pins 26, 28 should be tightly fitted intothe hole, either by screwing the same in or making a drive or force fitbetween the pins and the holes. It will be apparent that the fixing pinsmay, and preferably do, serve also as limit pins.

In the illustrative example, I have found that by locating all the pins22-28 at an angle of 4 also reduces the possibility of overheating of mmand lessening the tightness of their fit in the holes 28, 21.

The diameter of the pins is relatively small, good results being securedwhen said diameter is about equal to the thickness of the cracked wallbeing repaired. Typical diameters range from one-eighth to one inch. Dueto the manner in which both the fixing and limiting pins tie togetherthe walls of the crack and cause them to act Jointly as a single member,said pins are sometimes hereinafter referred to as an anchoringsystem.

The block 12 has the appearance shown in Fig. 2 subsequent toincorporation of the anchoring system.

nis pointed out that the fixing and 111mm pins cause a spreading tensionwhich also aids in preventing relative movement of the walls of thecrack in a direction along the crack. Channeling theerterior course ofthe oracle After the fixing and limit pins are applied, the externalsurface of the block is channeled along the course of the crack toprovide a groove 34 (Fig. 3). Said groove is so fashioned that itfollows the crack with the visible side of the crack runningsubstantially along the center of the bottom wall of the groove (seeFig. 4a) The grooving operation may be carried out in any manner wellknown to the art. as for example bygrinding or with a hammer and chisel.At

about 45 to the top surface of the block, highly satisfactory resultsare obtained. However, the angles at which said pins are inserted may bevaried at will as long as they still can assume any stress which wouldtend to relatively move the opposite walls of the repaired crack, and aslong as the fixing pins 22, 24 are in holes 23 so I located that theends of a crack do not extend across any portion of the same.

The pins can, as shown, be of such length that they project into thecirculating passageway I 8 of the water jacket, thereby making certainthat said pins have their temperature changed in advance of 'anychangein temperature experienced by a surrounding part of the block due tochange in temperature of the cooling medium. Projection of the pins intothe circulating passageway the. time the groove is formed, theprojecting ends of the pins 22--28 are removed and the groove is cutthrough said pins. The size and cross-sectional contour of the grooveare not critical. I have obtained satisfactory results with a V-shapedgroove having a rounded bottom wall and side walls sloped at an angle ofabout 60, the width and depth of the groove being about three-quartersof the thickness of the cracked wall of the block.

The foregoing sequence of steps may be modifled, if desired, to carryout the channeling operation before the fixing or limiting pins areinserted. In such case, it is preferable to dispose the head of the pinbelow the exposed surface of the block, e. g., the cylinder wall, valveseat or top of the block. It is further desirable, where such sequenceof steps is employed, to locate the head of the pin near the bottom ofthe groove or to countersink said pin in the groove, for reasons whichwill shortly be apparent.

Depositing metal in the groove After the anchoring system has beenapplied and the crack channeled, metal 36 is deposited in the groove byelectric bonding, it being remembered that the surface of the grooveincludes the heads of the fixing and limit pins as well as a part of theengine block, so that the electrically bonded metal will unitarily jointthe anchoring system and the block.

The term "electric bonding" as used herein denotes an operation whereinmetal is fused to and deposited upon a metallic surface from aconsumable metallic electrode which is touched to point after point ofsaid surface, while a low voltage, high amperage current flows throughthe electrode and surface. By way of example,

6 volts and 200 amperes are satisfactory current amperage may be variedconsiderably from, say,

I the repair ages.

$6 to 20 volts and 200 to 400 amperes. The metal of the electrode and ofthe metallic surface are fused together at their point of contact at themoment the electrode touches said surface whereby to firmly bond thedeposited metal to the surface. The current and voltage do not range sohigh as to deeply affect the metallic surface, as where an arc weldingvoltage and current are used. It may be mentioned that depositing metalin the groove by arc welding will not yield satisfactory results as insuch case, with the large current and amperage employed the block willbe heated deeply and create new stresses upon cooling which may giverise to further cracking. However, when metal is deposited in thechannel by electric bonding the heating of the block is only skin deepand no new local stresses are set up.

Any suitable metal may be deposited in the groove as, for example,nickel, iron, copper, brass and bronze. The use of nickel is preferredbecause the same has no tendency to oxidize or corrode under theconditions to which objects such as engine cylinder blocks are normallysubjected.

The electric bonding step may also include any additional processingwhich serves to compact the electrically bonded deposited metal, as forexample, rapidly vibrating the metallic electrode toward and away fromthe metallic surface and/or directing a stream of a gas non-combustiblewith air against the metal being de- Sufflcient electrically bondedmetal is deposited in the groove to build beyond the original sur faceof the block, 1. e., before channeling and/or wear, and after thisamount of metal is deposited the block may be subjected to ametal-removing operation to bring the level of the electricallybondeddeposited metal back to Such original surface. clude grinding,planing, shaping, milling, boring, chiseling and filing.

The repair now has the final finished appearance indicated in Fig. 4 andis characterized by the provision of an anchoring system which isolatesthe crack and prevents relative movement of the side walls thereof and abonding system which couples into an integral body the metal of theanchoring system and the surrounding body of the object being repaired.

Sealing the repair out. This comprises sealing the pores or intersticesin the deposited metal and the fine crevices around the pins.

- Although it is essential in carrying out my invention that the metalwithin the groove be applied by electric bonding in order to preventoverheating the bod while yet securing a good bond between the depositedmetal, the pins and said body, nevertheless m'etal deposited by electricbonding is inherently spongy and there is, therefore, a tendency forfluid to leak therethrough as well as through the hair line crack aroundthe pins.

It is for this reason that the final step of my invention is essential.

This step is performed by subjecting the block in the region of therepaired crack to the action Suitable metal-removing operations in-'Such leakage increases as at least partially into the electricallybonded metal and which includes a sealing material tion, or when thesolution is subjected to pressure in the presence of either heat orcold. Alternatively, the sealing material may be characterized by itsabilit to solidify from the solution merely upon exposure to air as, forexample,

upon dehydration. The solution must be readily removable from the blockwhere the material has not solidified and solidification of the materialmust be slow or controllable so that deposit of a large mass of a solidcan be prevented. Materials having the foregoing characteristics, andwhich, therefore, are capable of use in conjunction with my'invention toflll in the pores in the electrically bonded meta1 and the fine crevicesaround the pins, are the various alkali metal silicates, drying oils andground fiaxseed. The fluent vehicle preferably is water in which thesealing material is dissolved or dispersed.

In addition, the sealing solution may include dispersed powders ofmetals having atomic weights not less than that of aluminum. I havefound that these powders cause the sealing material to bond more firmlywith the metal of the article and of the repair. Examples of suchsubstances are aluminum, iron and copper, which have been comminuted byball milling to amorphous powders.

I have also obtained good results where the powdered iron is derived byreducing rouge (iron oxide), with hydrogen in a manner well known bychemists. The a resultant amorphous iron powder is extremely fine andpure] The sealing solution also may include a substance which will reactmildly with the metal of the article being repaired or that of the pinsor electrically bonded metal. This is believed to aid the sea] bycleaning the surfaces of the material in the crack or cleaning the pinsor electrically bonded metal and thereby enabling the sealing materialto cohere better in the repair. Such materials include, by way ofexample, sodium, magnesium and iron hydroxides,

If desired, the sealing solution may also comprise a filler, as forinstance, fuller's earth or alumina.

Another substance whose incorporation in the sealing solution increasesthe efficacy of the seal is any lithium compound which does not reactwith water, such compound including, by way of example, lithiumsilicate, hydroxide, chloride and nitrate.

Without limiting my invention thereto, I have given below examples ofvarious sealing solutions which will perform satisfactorily in thepractice of my invention, and of which each includes a plurality of theabove mentioned substances:

1 Example 1 Sodium silicate, 47 Baum gals 55 Fuller's earth lbs doCopper powder lbs 1 Aluminum powder; lbs 1 Flaxseedmeal lbs 1 or asealing solution which is caused to permeate Water gals 5 Theseingredients are thoroushly and intimately blended by placing the same ina fast mixer where they are worked for approximately two hours and thendrawn oi'f. The resulting mixture is a concentrated sealing solutionwhich is used by adding one pint thereof to six gallons of water. Weakeror stronger diluted solutions can also be employed. The diluted sealingsolution is particularly well suited for use in the repair of cracks inengine blocksin accordance with my invention. If said solution iscirculated past the electrically bonded metal at a rate of about 10cubic feet per minute and at a temperature of about 160 F. for about 20minutes. it will completely seal the pores in the electrically bondedmetal and the fine crevices around the pins.

It should be particularly noted that these pores and crevices are of aconsiderable lesser order of magnitude than the crack being repaired,and it is for this reason, I believe, that the sealing solution, whichat best could only serve as a temporary expedient to close the crack,will permanently seal the pores and crevices.

Example 2 Sodium silicate, 47 Baum cc 100 Potassium silicate, 405 Baumcc- 25 Amorphous iron (prepared by reducing iron oxide with hydrogen)grams 3 Powdered anhydrous alumina do Water I cc 35 The concentratedsealing solution is prepared by mixing the alumina and amorphous ironwith water and adding the mixture to the silicates which previously havebeen compounded. Said solution is diluted in a ratio from one pintthereof to about two to live gallons of water. The dilute sealingsolution, which sets by dehydration, is satisfactory for generaloperations. Due to the presence of the pure iron powder, the seal willbond particularly rapidly with the metal of the crackedarticle and willalso bond well with the pins and the electrically bonded metal.

Example 3 Sodium silicate -17 Baum cc 100 Potassium silicate, 40.5" Baumcc 5 Red iron oxide grams 3 soy bean oil cc 4 Sodium hydroxide grams 4Water -cc 25 The concentrated sealing solution is prepared by mixing thesodium hydroxide in half of the water, and then adding thereto the soybean oil and stirring the resulting mixture. The rest of the water isadded to this mixture and the same is then added to the silicates whichpreviously have been compounded and the entire fluid body mixed well.The concentrated sealing solution is diluted in the ratio of about fromone part thereof to about 200 to 5,000 parts of water. At theformerratio. particularly good results are obtained with sulphatedcastings. This sealing solution, in general, is useful in the repair ofcracked castings which are subjected to acids.

Example 4 Sodium silicate, 47 Baum cc 100 Potassium silicate, 405 Baumcc 5 Lithium silicate, 40 Baum cc 1 Magnesium hydroxide grams 0.2Anhydrous alumina powder do 0.4 Oleic acid ..do 0.2 Ferric hydroxide do0.1 Water -cc 20 The concentrated sealing solution is prepared by addingwater to a mixture of the alumina and the magnesium hydroxide insuiilcient quantities to make a thin paste. The oleic acid is added tosaid paste and the mass is heated to emulsify the same. Then, enoughwater is added to make a thin liquor. The ferric hydroxldeis added tothe silicates which previously have been compounded and the mixture isstirred well while adding to it the thin liquor. The concentratedsealing solution may be used in dilutions of about one part thereof tofrom about 1.000 to 50 parts of water. In dilute form, said solutionshows gOOd results in the repair of cracks for articles employed forheavy duty operation in salt water, and. in general for the repair ofcracks in heavy thick castings composed either of ferrous or non-ferrousalloys. Castings repaired in accordance with my invention and with theuse of this sealing solution, will stand a great deal of vibration, asthe seal is believed to be a heavy alkaline saponiiled gel, with goodsurface tension.

Although the alkali metal silicates described in the various foregoingexamples have all been illustrated as having the same viscosity, it willbe understood that these specific viscosities are only exemplitive.

Although I contemplate passing the solidinable fluent material overeither side of the electrically bonded metal, that is, either over thesurface of the hollow body which has been grooved and electricallybonded, or within the interior of said body, it is much simpler whenrepairing certain types of metallic castings to introduce the fluentpore-sealing material inside the body. This is particularly so where therepair is to be eifected in a body such as an engine block which hasinternal passageways adapted normally to-pass a circulating medium. Theonly drawback to the use of these passageways is that many of them openon the top face or the block and this would entail the laborious task ofrefastening the cylinder head on the block after repairing the crackand, possibly, subsequently removing said head to ascertain whether thecrack is completely repaired.

To aid in carrying out my invention I have provided an apparatus throughwhose use the circulating system of the block may be employed to receivesaid solldlflable fluent material without the tedious procedure ofmounting and subsequently dismounting the cylinder head. Said apparatuscomprises a plate 18 of such configuration that when superimposed on theengine block l2, it will close 011 all water passageways opening at thetop surface of said block. A satisfactory configuration is seen in Fig.6 wherein the openings 40 which normally furnish communication for acoolant between the cylinder block and the valve head are shown blockedoil by the plate 38. If desired, the Plate 38 may be lightened byproviding apertures 42 therein, matching the cylinder bores l6, and theplate Il may be skeletonized generally as long as it effectively blocksthe. openings I. Said .plate may also be provided with apertures 44 andindentations It to afford free passage for the cylinder head bolts 48.

In order to avoid the troublesome individual attachment of nuts ontheseveral bolts ll, I.

provide a single means to dctachably secure the plate 38 to a block.Said means comprises a spider 50 having a plurality of dependingcoplanar feet 5l which are adapted to rest on the 76 upper surface ofthe plate ll. These feet radiate from a central huh I! which isapertured to slidably receive and 54. Said rod, which is adapted toextend through a cylinder bore" It, carries a plate 56 at its lower endwhich engages the bottom of the block. The upper end of said rod isthreaded to receive a capstan nut 58. A washer 60 is interposed betweenthe nut II and hub 52.

The foregoing apparatus is employed in the following manner: After thecrack I. (Fig. '1) has been located, pinned, grooved, electricallybonded and had the exposed surfaces of the electrically bonded materialmachined, the block I! is placed upon the plate It and a gasket 62 ofthe type conventionally employed with the block I2 (but abbreviated tothe approximate contour of the plate 38) is placed upon the uppersurface of said block. Next, the blocking plate 38 is set on the gasketand the spider ll slipped on the rod 54. Then the nut 58 is threaded onsaid rod and is screwed fast. The block is now ready to have thepore-sealing fluent material introduced through the bottom radiatorconnection. If desired, said material may be circulated through theblock by employing another connection to the block as, for example, thedrain tap or one of the openings ll which may be left unblocked by theplate 38. Circulation is facilitated by using a flow unit including apump and heater. Several plates may be provided. one for eachdifferenttype of engine, or a single plate may be employed which is large enoughfor any block and which has a single aperture to receive only the rod54.

The above apparatus for closing the circulating openings in the top ofan engine block also may serve as a means for twting the repaired blockfor leakage, the same being accomplished merely by leaving the apparatusin place after said fluent material has been circulated through theblock and after sufficient time has elapsed to solidify said material inthe deposited metal. A fluent testing substance, such as a smoky gas orwater, is placed under pressure in said block, and if the crack is notrepaired, the testing material will leak therethrough.

It will further be appreciated that the solidiflable fluent material maybe circulated through the block under pressure and the repair watchedduring the period of circulation. When leaking stops, the repair will becompletely eflectuated. Thus, during this period, said apparatusfunctions both as a repairing means and as a testing means.

It may be mentioned that the method of repair described herein and theapparatus used in conjunction therewith is mostly used in connectionwith the repair of cracks in hollow cast bodies, inasmuch as, althoughwelding, due to its simplicity and economy, is ordinarily employed torepair cracks, cast bodies cannot be welded without an elaboratepre-treatment which renders the repair by welding of such bodies costlyin comparison with the method of repairing said bodies in accordancewith the present invention.

It will thus be seen that I have provided a method for repairing crackedhollow metallic bodies which achieves the several objectsof my inventionand which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention andas various changes might be made in the embodiment above set forth, itis to be understood that all matter he 10 in set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.

Having thus described my invention, I claim as new and desire to secureby Letters Patent:

1. A method of repairing a hollow cast body having a crack thereinextending from the hollow interior to the exterior thereof: said methodcomprising locating the crack, forming holes in the body from theexterior to the interior thereof through the ends of the crack, formingholes in the body from the exterior to the interior thereof at spacedpoints along the crack, tightly fitting pins in said holes whereby toisolate the crack from the sound portion of the cracked body and preventrelative movement of the walls of the crack along the crack, channelingthe exterior of said body along the course of the crack, and thendepositing sufilcient metal in the resulting groove and on the pins byelectric bonding to restore the original surface of the body.

2. A method of repairing a hollow cast body having a crack thereinextending from the hollow interior to the exterior thereof: said methodcomprising locating the crack, forming holes in the body from theexterior to the interior thereof through the ends of the crack, formingholes in the body from the exterior to the interior thereof at spacedpoints along the crack, where stressing of the body after repair of thecrack would cause relative movement of the walls of the crack in adirection along the crack, tightly fitting pins in said holes whereby toisolate the crack from the sound portion of the cracked body and preventrelative movement .of the walls of the crack along the crack, channelingthe exterior of said body along the course of the crack, and thendepositing sufficient metal in the resulting groove '"and on the pins byelectric bonding to restore the original surface of the body.

3. A method of repairing a hollow cast body having a crack thereinextending from the hollow interior to the exterior thereof: said methodcomprising locating the crack, forming holes in the body from theexterior to the interior thereof through the ends of the crack, formingholes in the body from the exterior to the interior thereof at spacedpoints along the crack, tightly fitting pins in said holes whereby toisolate the crack from the sound portion of the cracked body and preventrelative movement of the walls of the crack along the crack, channelingthe exterior of said body along the course of the crack, then depositingsuilicient metal in the resulting groove and on the pins by electricbondingto restore the original surface of the body, the crevices aroundthe pins and the pores in the deposited metal being of a lesser order ofmagnitude than the crack, and sealing the pores in the deposited metaland the fine crevices around the pins, by introducing into the interiorof said body in the region of the crack a fluent material which willpermeate at least partially into said crevices and pores and solidifytherein. 7

4. A method of repairing a hollow cast body having a crack thereinextending from the hollow interior to the exterior thereof: said methodcomprising locating the crack, forming holes in the body from theexterior to the interior thereof through the ends of the crack, formingholes in the body from the exterior to the interior thereof at spacedpoints along the crack, tapping said holes, tightly screwing threadedpins in said holes whereby to isolate the crack from the sound portionof the cracked body and prevent relative 1 movement of the walls of thecrack along the crack, channeling the exterior of said body along thecourse of the crack, then depositing sumcient metal in the resultinggroove and on the pins by electric bonding to restore the originalsurface of the body, the crevices around the pins and the pores in thedeposited metal being of a lesser order of magnitude than the crack, andsealing the pores in the deposited metal and the flne crevices aroundthe pins, by introducing into the interior of said body in the region ofthe crack a fluent material which will permeate at least partially intosaid crevices and pores and solidify therein.

5. A method as set forth in claim 4 wherein the upper ends of the pinsare placed below the original surface of the body before metal isdeposited by electric bonding.

DUDLEY ANSON MERCER.

12 emcee cn'm Theiollowingretmandmdinthe flleolthispatentz UNII'ID STATEPHI-ITS Number Name Date 1,019,532 Balm llar. 5, 1912 1,452,936 BchumanApr. 24, 1923 1,645,585 Burton Oct. 16, 1927 1,648,065 Ray Nov. 8, 192'!1,648,866 Ray Nov. 8, 1927 2,011,464 Harman Aug. 13, 1936 7 2,178,156Aulbach Oct. 31, 1939 2,228,087 Rose Jan. 7, 1941 2,252,986 Beott Aug.19, 1941 2,267,033 Kerkling Dec. 23, 1941 Re.22,39'l Meduna Nov. 30,1943 2,361,106 Jensen Oct. 24, 1944 2,410,464 Scott Nov. 0, 1940

